"The ruling Wednesday by U.S. District Judge Susan Bolton clears the way for police to carry out the 2010 law's requirement that officers, while enforcing other laws, question the immigration status of those they suspect are in the country illegally."

Bolton did, however, grant a "preliminary injunction against a statute making it illegal to harbor individuals suspected of being in the country illegally," according to the Arizona Republic newspaper.

The U.S. Supreme Court upheld the provision in June while striking down other parts of the state's contentious immigration law. After that decision, opponents of the law argued that it would lead to racial profiling and asked Bolton to block it.

As NPR's Nina Totenberg reported at the time, the Supreme Court in its 5-3 decision warned that it could ultimately strike down the "show me your papers" provision, too.

Here's what Nina said at the time:

"But in a clear warning shot across the bow, the court emphasized that its ruling could change depending on how the law is actually enforced on the ground. Justice Kennedy suggested there would be clear constitutional problems if the law were used to target racial or ethnic minorities, or to detain people for an unreasonable period of time while checking their immigration status.

"For now, though, the court said it was willing to wait and see what happens."

Parts of the law have been in effect for more than two years. Arizona Gov. Jan Brewer's office says the law is expected to go into effect shortly.

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